Rebalancing

You have carefully chosen your target asset allocation — say, 70% stocks and 30% bonds. But over time, as different investments grow at different rates, your portfolio will drift away from that target. Rebalancing is the disciplined process of bringing it back. In this lesson, we explore why rebalancing matters, the different approaches you can use, and how to do it in a tax-efficient way.

Disclaimer: This is educational content, not financial advice. Always consult a qualified financial professional before making investment decisions.

Why Portfolios Drift

Portfolio drift occurs because different asset classes grow at different rates. If stocks have a strong year and bonds have a flat year, the stock portion of your portfolio will grow larger relative to bonds. Over time, this drift can significantly change your portfolio's risk profile without you making any active decision.

Consider this example: you start with a 70/30 stock/bond allocation. After a strong bull market where stocks gain 30% and bonds gain 3%, your portfolio would drift to approximately 78/22. That may not sound like a big change, but it means your portfolio is now significantly more aggressive than you intended, with roughly 11% more exposure to stock market volatility.

What Is Rebalancing?

Rebalancing is the process of realigning your portfolio back to your target allocation. Using the example above, you would sell some of your stock holdings and use the proceeds to buy more bonds, restoring the 70/30 split. Alternatively, you could direct new contributions entirely toward bonds until the balance is restored.

At its core, rebalancing is a disciplined strategy of selling what has performed well (the overweight asset) and buying what has underperformed (the underweight asset). This is counterintuitive — our natural instinct is to buy more of what is going up and sell what is going down. But rebalancing enforces a systematic "buy low, sell high" discipline that can improve risk-adjusted returns over time.

When to Rebalance: Calendar vs. Threshold

There are two main approaches to deciding when to rebalance:

Calendar Rebalancing

With calendar rebalancing, you check and adjust your portfolio on a fixed schedule — monthly, quarterly, semi-annually, or annually. You pick a date (or dates) and rebalance regardless of how much drift has occurred. This approach is simple, predictable, and easy to remember.

Research suggests that annual rebalancing is often sufficient. Studies comparing monthly, quarterly, and annual rebalancing have found minimal differences in long-term results. Rebalancing too frequently can actually increase trading costs and tax consequences without providing meaningful risk reduction.

Threshold Rebalancing

With threshold rebalancing, you rebalance whenever any asset class drifts beyond a predetermined percentage from its target. For example, if your target is 70% stocks and you set a 5% threshold, you would rebalance whenever stocks exceeded 75% or fell below 65% of your portfolio. This approach rebalances only when needed, which can be more efficient during stable market periods.

Many advisors recommend a combined approach: check your portfolio on a regular schedule (such as quarterly), but only rebalance if any asset class has drifted more than 5% from its target. This captures the simplicity of calendar rebalancing while avoiding unnecessary transactions.

How to Rebalance

There are several methods for bringing your portfolio back to its target allocation:

• Sell and buy: Sell some of the overweight asset and use the proceeds to purchase more of the underweight asset. This is the most direct method but may trigger capital gains taxes in taxable accounts.
• Direct new contributions: Instead of investing new money proportionally, direct all new contributions (such as monthly 401(k) deposits or additional investments) to the underweight asset class until balance is restored. This avoids selling altogether.
• Redirect dividends and distributions: Rather than reinvesting dividends and interest payments back into the same fund, direct them to the underweight asset class.
• Use cash flows: When you need to withdraw money from your portfolio (in retirement, for instance), withdraw from the overweight asset class to bring it back toward target.

Tax-Efficient Rebalancing Strategies

Minimizing the tax impact of rebalancing requires a thoughtful approach:

• Rebalance in tax-advantaged accounts first: Selling and buying within a 401(k), IRA, or Roth IRA triggers no immediate taxes. If your portfolio spans both taxable and tax-advantaged accounts, do your rebalancing trades in the tax-advantaged accounts whenever possible.
• Use new contributions: The most tax-efficient rebalancing method is to direct new money to the underweight asset class rather than selling the overweight one. This gradually restores balance without triggering any taxable events.
• Tax-loss harvesting: If some of your investments are at a loss, you can sell them to rebalance and simultaneously capture a tax deduction. The capital loss can offset capital gains from other sales, reducing your overall tax bill. Just be mindful of the wash-sale rule, which prohibits buying a "substantially identical" security within 30 days of selling at a loss.
• Use income distributions: Direct dividend and interest payments to the underweight asset class instead of automatically reinvesting them in the same fund.

The Discipline of Selling Winners and Buying Laggards

Rebalancing requires going against your instincts. When stocks have had a great run and bonds have lagged, every fiber of your being may want to add more to stocks because they are "winning." Selling stocks to buy bonds feels wrong in the moment. But this counterintuitive discipline is exactly what keeps your risk level in check and enforces the buy-low, sell-high principle.

During the dot-com bubble of the late 1990s, investors who let their portfolios drift toward heavily stock-weighted allocations suffered devastating losses when the bubble burst in 2000-2002. Those who disciplined themselves to rebalance — selling some of their surging stocks to buy bonds — preserved more of their wealth and recovered faster. Rebalancing is not about maximizing returns in any single year; it is about maintaining the risk level that is right for your goals over the long term.

Automatic Rebalancing Options

Many investment platforms now offer automatic rebalancing features. Target-date funds rebalance internally as part of their management. Robo-advisors like Betterment and Wealthfront automatically rebalance your portfolio when it drifts beyond set thresholds. Many 401(k) plans offer an automatic rebalancing option that you can set and forget.

If you prefer a hands-off approach, these tools can handle rebalancing for you. The most important thing is that rebalancing happens regularly, whether you do it manually or let technology handle it.

Key Takeaways

• Portfolio drift occurs naturally as different asset classes grow at different rates, changing your risk profile over time
• Rebalancing restores your portfolio to its target allocation, maintaining your intended level of risk
• Calendar rebalancing (annual is often sufficient) and threshold rebalancing (5% drift trigger) are the two main approaches
• Rebalancing enforces a disciplined "buy low, sell high" approach that can provide a small return bonus
• Tax-efficient rebalancing prioritizes tax-advantaged accounts, new contributions, and tax-loss harvesting
• Directing new money to underweight assets is the simplest and most tax-efficient rebalancing method
• Automatic rebalancing through target-date funds, robo-advisors, or 401(k) features makes the process effortless

Disclaimer: The content on financeforest is for educational purposes only and does not constitute financial advice. Always consult a qualified financial advisor before making investment decisions.